Recently, there has been a frequent occurrence of abnormal weather in association with global warming. Many glaciers in the polar regions have been reported to be melting due to global warming. It has been predicted that the abnormal weather will destroy or change the global ecosystem greatly. To maintain safe and life-friendly environments for future generations, it is necessary to prevent such environmental disruptions that are due to global warming. Amain reason for global warming is thought to be the emission of a large amount of carbon dioxide into the atmosphere. This happens because, in modern civilization, energy is obtained mainly by burning fossil fuels such as coal and oil. To obtain energy while preventing global warming, accordingly, an energy source is needed which does not depend on conventional fossil fuels.
As such new energy sources, wind power and sunlight have been focused on. In consideration of this, wind power generation and solar power generation are being actively researched and developed in various countries.
In the meantime, to use generated electricity as a commercial power supply, inverters are required for wind power generation and solar power generation. However, wind power generation and solar power generation are adapted to different rated voltages, and hence a dedicated inverter has needed to be developed for each method of power generation. This causes delays in the release of newly developed wind power generators to the market and decreases the compatibility between wind power generators and solar power generators. Accordingly, ideas are needed for applying general purpose inverters to the generators and, in particular, to wind power generators.